WO2013081375A1 - Battery module and bus bar applied to battery module - Google Patents

Abstract

The present invention provides a battery module, which can ensure the safety of use of the invention by breaking a bus bar if an overcurrent flows in the battery module due to an abnormal operation of a protection circuit. The battery module according to the present invention comprises: at least one unit cell; a case which accommodates the unit cell therein; and a bus bar which is electrically connected to the unit cell, wherein the bus bar comprises: a first metal plate; a second metal plate which is positioned to be spaced from the first metal plate; and a metal bridge which connects the first metal plate with the second metal plate, and has a lower melting point than the metal plates.

Description

Bus Bar Applied to Battery Module and Battery Module

The present invention relates to a battery module with improved safety during a short circuit and a bus bar applied thereto. The present invention relates to a battery module and a bus bar having improved structure to prevent explosion or ignition caused by an increase in temperature inside a battery due to a short circuit. .

This application claims the priority based on Korean Patent Application No. 10-2011-0125225, filed November 28, 2011, and all the contents disclosed in the specification and drawings of the application are incorporated in this application.

In addition, this application claims the priority based on Korea Patent Application No. 10-2012-0135793 filed on November 28, 2012, all the contents disclosed in the specification and drawings of the application is incorporated in this application.

As the use of portable electric products such as video cameras, portable telephones, and portable PCs is activated, the importance of secondary batteries mainly used as driving power thereof is increasing.

Unlike primary batteries that are not normally rechargeable, rechargeable batteries can be recharged by active development of high-tech fields such as digital cameras, cellular phones, laptop computers, power tools, electric bicycles, electric vehicles, hybrid vehicles, and large-capacity power storage devices. Research is ongoing.

In particular, lithium secondary batteries have a higher energy density per unit weight and can be rapidly charged compared to other secondary batteries such as lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries, thereby increasing their use actively. It's going on.

Lithium secondary battery is used as a power source for portable electronic devices with an operating voltage of 3.6V or more, or by connecting a plurality of batteries in series or in parallel to high power electric vehicles, hybrid vehicles, power tools, electric bicycles, power storage devices, UPS, etc. Used.

Lithium secondary batteries have a three times higher operating voltage than nickel-cadmium batteries or nickel-metal hydride batteries, and are also rapidly being used because of their excellent energy density per unit weight.

The lithium secondary battery may be classified into a lithium ion battery using a liquid electrolyte and a lithium ion polymer battery using a polymer solid electrolyte according to the type of electrolyte. Lithium ion polymer batteries can be classified into fully solid lithium ion polymer batteries containing no electrolyte solution and lithium ion polymer batteries using gel polymer electrolyte containing electrolyte solution, depending on the type of polymer solid electrolyte.

In the case of a lithium ion battery using a liquid electrolyte, a cylindrical or rectangular metal can is used as a container by welding sealing. Since the can-type secondary battery using such a metal can as a container has a fixed shape, there is a disadvantage in restricting the design of an electric product using the same as a power source, and it is difficult to reduce the volume. Therefore, a pouch type secondary battery using an electrode assembly and an electrolyte in a pouch packaging material made of a film and sealing it has been developed and used.

However, the lithium secondary battery is one of the important problems to ensure safety because there is a risk of explosion when overheating. Overheating of the lithium secondary battery is caused by a variety of causes, one of which is the case in which overcurrent flows beyond the limit through the lithium secondary battery. When the overcurrent flows, the lithium secondary battery generates heat by Joule heat, so the internal temperature of the battery increases rapidly. The rapid rise in temperature also causes decomposition reactions of the electrolyte, causing thermal running, which eventually leads to battery explosion. The overcurrent is a rush current due to a breakdown of the insulation between the positive electrode and the negative electrode due to a sharp metal object penetrating the lithium secondary battery, the contraction of the separator interposed between the positive electrode and the negative electrode, or an abnormality in the charging circuit or load connected to the outside. Occurs when is applied to a battery.

Therefore, a lithium secondary battery is used in combination with a protection circuit to protect the battery from an abnormal situation such as the occurrence of an overcurrent. The protection circuit includes a fuse device irreversibly disconnecting a line through which charge or discharge current flows when an overcurrent occurs. It is common to include.

1 is a circuit diagram illustrating an arrangement structure and an operation mechanism of a fuse device among components of a protection circuit coupled to a battery module including a lithium secondary battery.

As shown in the figure, the protection circuit operates the fuse device 10 when the overcurrent occurs by monitoring the fuse device 10, the sense resistor 20 for overcurrent sensing, and the overcurrent to protect the battery module when the overcurrent occurs. The microcontroller 30 and the switch 40 for switching the flow of the operating current to the fuse element 10.

The fuse element 10 is installed on a main line connected to the outermost terminal of the battery module. The main line is the wiring through which the charging or discharging current flows. In the figure, the fuse element 10 is shown installed in a high potential line Pack +.

The fuse element 10 is a three-terminal element component, and two terminals are connected to a main line through which charging or discharging current flows, and one terminal is connected to the switch 40. The inside includes a fuse 11 connected in series with a main line and having a fusion at a specific temperature, and a resistor 12 for applying heat to the fuse 11.

The microcontroller 30 periodically detects a voltage across the sense resistor 20 to monitor whether overcurrent occurs, and turns on the switch 40 when it is determined that overcurrent has occurred. Then, the current flowing in the main line is bypassed to the fuse element 10 and applied to the resistor 12. Accordingly, the joule heat generated from the resistor 12 is conducted to the fuse 11 to raise the temperature of the fuse 11, and when the temperature of the fuse 11 rises to the melting temperature, the fuse 11 is fused to form a main heat. The track is irreversibly disconnected. If the main line is disconnected, the overcurrent no longer flows, thus eliminating the problem caused by the overcurrent.

However, the above-described prior art has various problems. That is, when a failure occurs in the microcontroller 30, the switch 40 is not turned on even in a situation in which an overcurrent occurs. In this case, since the current does not flow into the resistor 12 of the fuse element 10, there is a problem that the fuse element 10 does not operate. In addition, a space for disposing the fuse element 10 in the protection circuit is required separately, and a program algorithm for controlling the operation of the fuse element 10 must be loaded in the microcontroller 30. Therefore, there is a disadvantage in that the space efficiency of the protection circuit is lowered and the load of the microcontroller 30 is increased.

The present invention was conceived in consideration of the prior art as described above, by configuring a bus bar connecting between the cell and the external terminal in a double structure, when the temperature rises due to abnormal phenomenon during use of the battery module is easily broken bus bar By providing a battery module and a bus bar that can be applied to ensure the safety of the use.

Battery module according to the present invention for achieving the above technical problem, at least one unit cell; A case accommodating the unit cell; A bus bar electrically connected to the unit cell, wherein the bus bar comprises: a first metal plate; A second metal plate positioned to be spaced apart from the first metal plate; And a metal bridge connecting between the first metal plate and the second metal plate and having a melting point lower than that of the metal plate.

Preferably, the metal bridge may include tin (Sn) and copper (Cu) as main components.

The content of tin is 80 to 98wt%, the content of copper is preferably in the range of 2 to 20wt%.

Optionally, the metal bridge may further include at least one additional metal selected from nickel (Ni), zinc (Zn), and silver (Ag), in which case the content of the additional metal is preferably 0.01 to 10 wt%. Do.

The metal bridge is preferably formed to have a melting point of 150 to 300 ℃.

Preferably, the first metal plate and the second metal plate may be located on the same plane with a predetermined gap.

According to an aspect of the present invention, the metal bridge may be joined to the first metal plate and the second metal plate on either or both sides of the first metal plate and the second metal plate.

According to another aspect of the invention, the first metal plate and the second metal plate has a receiving groove formed on at least one of the upper surface or the lower surface of each one end facing each other, the metal bridge and the groove It has a corresponding size and shape, can be accommodated in the space formed by the interlocking of the groove and bonded to the first metal plate and the second metal plate.

According to another aspect of the invention, the first metal plate and the second metal plate has a first bent portion and a second bent portion formed on each side end facing each other, the metal bridge is the first bent portion And it is accommodated in the space formed by the interlocking of the second bent portion can be bonded to the first metal plate and the second metal plate.

According to another aspect of the invention, the first metal plate and the second metal plate has a receiving groove formed in a predetermined depth from the surface facing each other, the metal bridge, one side and the other side is inserted into the receiving groove, respectively Can be joined with the metal plate.

According to another aspect of the present invention, the metal bridge may be directly interposed between the surface where the first metal plate and the second metal plate are opposed to each other and bonded to the first metal plate and the second metal plate.

The opposite surface may have an inclined surface tapered in the metal soldering bridge direction.

According to another aspect of the present invention, one side of each of the first metal plate and the second metal plate is positioned so that at least a portion overlaps to face each other, the metal bridge is interposed in the facing area and the first metal plate and It can be joined with the second metal plate.

According to another aspect of the present invention, one side of each of the first metal plate and the second metal plate is at least partially overlapping each other and positioned to face each other, the metal bridge is one side and the other side facing each other of the circumference of the facing area Can be formed on.

Preferably, one side of each of the first metal plate and the second metal plate is positioned so that at least a portion thereof overlaps to face each other, and the metal bridge may be formed in the entire circumference of the facing area.

The rivet may further include a rivet for fixing between the first metal plate and the metal bridge and between the second metal plate and the metal bridge.

Preferably, the first metal plate and the second metal plate may have a tapered shape so that one side facing each other becomes narrow toward the end.

The battery module may further include an external terminal installed at one side of the case, and the bus bar may be installed to connect between the unit cell and the external terminal.

According to an aspect of the present invention, there is provided a battery module including: at least one unit cell including a positive lead and a negative lead; A case accommodating the unit cell; A first bus bar connected to the anode lead; And a second bus bar connected to the cathode lead, wherein the second bus bar comprises: a first metal plate; A second metal plate positioned to be spaced apart from the first metal plate; And a metal bridge connecting between the first metal plate and the second metal plate and having a melting point lower than that of the metal plate.

On the other hand, the bus bar according to the present invention for achieving the technical problem is a bus bar applied to the battery module, the first metal plate; A second metal plate positioned to be spaced apart from the first metal plate; And a metal bridge connecting between the first metal plate and the second metal plate and having a melting point lower than that of the metal plate.

According to the present invention, when the overload current flows to the battery module because the protection circuit does not operate normally, the bus bar is quickly broken, thereby bringing an effect of securing safety in using the battery module.

The following drawings attached to this specification are illustrative of the preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a circuit diagram illustrating an arrangement structure and an operation mechanism of a fuse device among components of a protection circuit coupled to a battery module.

2 is an exploded perspective view of a battery module according to a preferred embodiment of the present invention.

3 is a perspective view illustrating a state in which a battery cell and a bus bar constituting a battery module according to an exemplary embodiment of the present invention are combined.

Figure 4a is a complete perspective view of a battery module according to a preferred embodiment of the present invention.

4B is a front view of the battery module shown in FIG. 4A.

5 to 9C are perspective views of part A of FIG. 4B, and are partial perspective views illustrating various forms of a bus bar according to an exemplary embodiment of the present invention.

10 is a partial perspective view showing the shape of a bus bar according to another embodiment of the present invention.

11 is a partial perspective view showing the shape of a bus bar according to another embodiment of the present invention.

12 is a graph showing the results of a short circuit test for the battery module according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

First, the overall configuration of the battery module according to the present invention will be described with reference to FIGS. 2 to 4B.

2 to 4B, the battery module 1 according to the present invention includes a battery cell 100, a bus bar 200, a case 300, an external terminal 311, and a voltage sensor 321. .

The battery cell 100 is formed by stacking unit modules 100A, 100B, 100C, and 100D including at least one unit cell 110A and 110B and a cell cover 120 surrounding the unit cells 110A and 110B. do.

The unit cells 110A and 110B are connected to the electrode assembly (not shown) accommodated in the packaging material and the uncoated parts of the first and second electrode plates of the electrode assembly, respectively, and are drawn out in one direction and the other direction of the packaging material, respectively. And a lead 111 and a second electrode lead 112. In the present invention, a case in which the first and second electrode plates are a positive electrode plate and a negative electrode plate will be described as an example. Accordingly, the first and second electrode leads 111 and 112 are respectively the positive lead and the negative electrode leads 111 and 112. Let's explain.

The cathode plate is made of aluminum (Al), and the anode plate is generally made of copper (Cu). Therefore, in view of minimizing weldability and electrical resistance between the electrode plates and the electrode leads 111 and 112, the anode lead 111 is made of the same aluminum (Al) material as the anode plate, and the cathode lead 112 is the same copper as the cathode plate. It is preferable that the material is made of (Cu) material or nickel (Ni) coated copper (Cu) material.

In the case where the unit cells 110A and 110B and the unit modules 100A to 100D are plural, the connection between the unit cells 110A and 100B and the connection between the unit modules 100A to 100D may be performed according to the purpose of the battery. Although it may be connected in series or in parallel, in the present invention will be described taking the case of a serial connection as an example. That is, in the present invention, the unit cells 110A and 100B are connected to each other by coupling the anode lead 111 of one unit cell 110A and the cathode lead 112 of the adjacent unit cell 110B to each other. In this case, the anode lead 111 of the unit cell 110A located at the outermost side of the rear part (R direction) and the cathode lead 112 of the unit cell 110B located at the outermost part of the front part (F direction) will be described later. It is coupled with the bus bar 200 to be.

On the other hand, the number of the unit cells (110A, 110B) and the unit modules (100A ~ 100D) in the present invention only shows a case where there are two unit cells (110A, 110B), the unit modules (100A ~ 100D) is four Although only the stacked case is shown, this is merely an example and thus it is not limited to the number of the unit cells (110A, 110B) and the unit module (100A ~ 100D).

The bus bar 200 is the positive lead 111 of the unit cell 110A positioned at the outermost rear portion R of the battery cell 100 and the negative lead of the unit cell 110B positioned at the outermost portion of the front portion F. As coupled to 112, it includes a metal bridge 230 connecting the first metal plate 210, the second metal plate 220, and the metal plates 210, 220.

The bus bars 200 attached to the positive lead 111 and the negative lead 112 may be formed of different materials of the metal plates 210 and 220. That is, the metal plates 210 and 220 of the bus bar 200 attached to the positive electrode lead 111 are made of the same aluminum material as the positive electrode lead 111 and the metal plate of the bus bar 200 attached to the negative electrode lead 112. The 210 and 220 are preferably made of the same copper or nickel coated copper material as the cathode lead 112. However, since the configuration except for the material is the same, the present invention will be described based on the bus bar 200 attached to the anode lead 111.

The first metal plate 210 and the second metal plate 220 are made of a thin plate metal. The first metal plate 210 has a lead coupling portion 211 formed at one side thereof bent in a substantially '-' shape. The lead coupling portion 211 is coupled to one end of each of the electrode leads 111 and 112 by welding. The second metal plate 220 is positioned to be spaced apart from the first metal plate 220 by a predetermined distance, and the external terminal 311 may be inserted into an end opposite to the side where the first metal plate 210 is located. The terminal groove 220a is formed.

The metal bridge 230 connects the metal plates 210 and 220, and various embodiments of the concrete connection structure will be described later in detail with reference to FIGS. 5 to 11, and only roles and properties thereof will be described herein. Let's explain.

The metal bridge 230 melts when the battery module 1 is overheated, thereby releasing an electrical connection between the first metal plate 210 and the second metal plate 220. Preferably, the metal bridge 230 includes tin (Sn) and copper (Cu) as a main component, and is made of a lead-free alloy material containing no lead (Pb), which is harmless to the environment and human body, and is approximately 150 to 300 ° C. Has a melting point of. This melting point range is lower than the melting point of any one metal selected from aluminum, copper, or nickel-coated copper constituting the leads 111 and 112 and / or the metal plates 210 and 220, so that overcurrent can be quickly blocked. Do.

Melting point range of the metal bridge 230 is the maximum voltage and current conditions that the bus bar 200 must withstand, the level of overcurrent to be blocked using the bus bar 200, the electrical properties required for the bus bar 200 It is determined in consideration of (resistance) and / or mechanical properties (tensile strength). When the melting point of the metal bridge 230 is lower than 150 ° C., the bus bar 200 may be broken even in a current caused by the normal operation of the battery module 1. In addition, when the melting point of the metal bridge 230 is higher than 300 ℃ there is a problem that the blocking of the overcurrent is not effective.

The content of tin and copper included in the metal bridge 230 is appropriately adjusted according to the melting point of the metal bridge 230, the electrical and / or physical properties to be applied to the metal bridge 230 or the bus bar 200. This is possible.

Tin among the components of the metal bridge 230 affects the melting point and the tensile strength characteristics of the metal bridge 230. The content of tin is controlled in the range of 80 wt% or more, preferably 85 to 98 wt% so that the metal bridge 230 has a melting point of 150 to 300 ° C. and has good tensile strength. Here, the wt% is the same as a unit based on the total weight of the material constituting the metal bridge 230.

Among the components of the metal bridge 230, copper affects the electrical conductivity, melting point, and tensile strength of the bus bar 200, and in view of the function of copper, the copper content is preferably in the range of 2 to 20 wt%. Preferably in the range of 4-15 wt%.

By adjusting the content of tin and copper as described above, not only can the good tensile strength characteristics of the metal bridge 230 be obtained, but also the increase in resistance by the metal bridge 230 can be suppressed to a few percent or less, and the metal It is possible to adjust the melting point of the bridge 230 in the range of 150 to 300 ° C.

Optionally, the metal bridge 230 may further include any one or more metals selected from nickel (Ni), zinc (Zn), and silver (Ag) to improve electrical and / or mechanical properties. The amount of the additional metal may be adjusted according to the electrical and / or mechanical properties to be applied to the metal bridge 230, and may be adjusted in the range of 0.01 to 10 wt%.

Meanwhile, in the drawings of the present invention, only the case where the structure of the bus bar 200 is applied to both the anode lead 111 and the cathode lead 112 is illustrated, but it is also possible to apply to any one of the leads. In addition, when the structure of the bus bar 200 is applied to only one of the leads, it is generally applied only to the cathode lead 112 having a larger heat generation amount, and that the structure of the general bus bar is applied to the anode lead 111. desirable.

The case 300 accommodates the battery cell 100 and includes a lower case 310 and an upper case 320.

The lower case 310 is formed in an upwardly open structure to surround portions of both sides and a lower surface of the battery cell 100, and includes a pair of slits 310a. The slit 310a is formed at a position corresponding to the lead coupling portion 211 of the bus bar 200 on one side of the lower case 310 so that the lead when the battery cell 100 is inserted into the lower case 310. It provides a space in which the coupling portion 211 can be accommodated. Therefore, the battery cell 100 and the bus bar 200 are positioned inside and outside the lower case 310, respectively, while maintaining an electrical connection therebetween.

Meanwhile, an external terminal 311 formed to protrude outwardly of the lower case 310 is provided at a position corresponding to the terminal groove 220a of the bus bar 200 among one side of the lower case 310. The external terminal 311 is formed in a size and shape corresponding to the terminal groove 220a of the bus bar 200 so that the external terminal 311 is connected to the bus bar when the battery cell 100 is accommodated in the lower case 310. It provides a space that can be inserted into the 200, and serves to electrically connect the external device (not shown) and the battery cell 100. In terms of minimizing contact resistance between the external terminal 311 and the bus bar 200, the external terminal 311 and the bus bar 200 may be coupled by welding.

The upper case 320 is formed in a downwardly open structure to surround both sides of the battery cell 100 inserted into the lower case 310, that is, a part of the surface from which the electrode leads 111 and 112 are drawn out, and an upper surface thereof. It may be coupled to the lower case 310 by bolt coupling.

On the other hand, the upper case 320 has a sensor coupling portion (320a) formed to be inserted into the voltage sensor 321 on both sides. The voltage sensor 321 is electrically connected to the battery cell 100 in the voltage sensor coupling unit 320a to sense the voltage of the battery cell 100.

As described above, the battery module 1 according to the present invention is applied to the bus bar 200 having a dual structure connecting the metal plates 210 and 220 with the metal bridge 230. Therefore, when the overcurrent occurs, the battery module 1 may ensure the safety in use by quickly breaking the bus bar 200. In particular, the battery module 1 is applied to the bus bar 200, which is a component installed outside the case, so that the battery module 1 is ignited as compared to the case where it is applied to a component adjacent to an electrode assembly (not shown) such as the leads 111 and 112. And further reduce the risk of explosion.

Next, various embodiments according to the coupling form between the metal plates 210 and 220 and the metal bridge 230 will be described with reference to FIGS. 5 through 11.

First, the structure of the bus bar 200a according to the exemplary embodiment of the present invention will be described with reference to FIGS. 5 to 9C.

5 to 10 illustrate various forms of the bus bar 200a according to an embodiment of the present invention, wherein the bus bar 200a has a metal bridge 230 coupled to the metal plates 210 and 220 by welding. Is formed. That is, the metal bridge 230 serves as a soldering bridge connecting the metal plates 210 and 220 to each other.

Referring to FIG. 5, the first metal plate 210 and the second metal plate 220 are positioned on the same plane with a predetermined gap therebetween, and the metal bridge 230 is formed on the upper surfaces of the metal plates 210 and 220. To be bonded to the metal plates 210 and 220. In FIG. 5, only the case where the metal bridge 230 is formed on the upper surfaces of the metal plates 210 and 220 is illustrated. However, the metal bridge 230 may be formed on the lower surface. In addition, as shown in FIG. 6, the metal bridge 230 may be formed on both the upper and lower surfaces of the metal plates 210 and 220, and in this case, the metal bridges 210 and 220 may have an effect of strengthening the mutual bonding force. Can be.

Referring to FIG. 7A, the first metal plate 210 and the second metal plate 220 are disposed on the same plane with a predetermined gap therebetween, and receive the receiving groove RG1 formed on an upper surface of one end portion facing each other. Equipped. On the other hand, the metal bridge 230 has a size and shape corresponding to the receiving groove RG2, is accommodated in the space formed by the interlocking of the receiving groove RG1 is bonded to the metal plates (210, 220). In FIG. 7A, only the case where the accommodating groove RG1 is formed on the upper surfaces of the metal plates 210 and 220 is illustrated. However, the receiving groove RG1 may be formed on the lower surface or on both the upper and lower surfaces.

Referring to FIG. 7B, the first metal plate 210 and the second metal plate 220 may be disposed on the same plane with a predetermined gap therebetween, and may be formed with first bent portions 210 formed at one end portions facing each other. ') And the second bent portion 220'. On the other hand, the metal bridge 230 is accommodated in the space formed by the interlocking of the first bent portion 210 'and the second bent portion 220' is bonded to the metal plates (210, 220).

Referring to FIG. 7C, the first metal plate 210 and the second metal plate 220 are disposed on the same plane with a predetermined gap therebetween, and receive a receiving groove RG2 formed at a predetermined depth from surfaces facing each other. Equipped. On the other hand, one side and the other side of the metal bridge 230 is inserted into the receiving groove RG2 and bonded to the metal plates 210 and 220.

7A, 7B, and 7C have a larger bonding area between the metal plates 210 and 220 and the metal bridges 230 than the structures shown in FIGS. 5 and 6, thereby increasing the bonding force between the metal plates 210 and 220. In addition to the effect of strengthening the effect of reducing the contact resistance can also be brought.

Referring to FIG. 8A, the first metal plate 210 and the second metal plate 220 are disposed on the same plane with a predetermined gap therebetween, and the metal bridge 230 may have the metal plates 210 and 220 facing each other. It is directly interposed between the surfaces where it is in contact with the metal plates (210, 220).

The structure shown in FIG. 8B differs from the structure shown in FIG. 8A in that the opposing surfaces of the metal plates 210 and 220 have an inclined surface tapered in the metal bridge direction. In this case, as the contact area between the metal plates 210 and 220 and the metal bridge 230 becomes wider, not only the effect of strengthening the bonding force between the metal plates 210 and 220 but also the effect of reducing the contact resistance is also obtained.

Referring to FIG. 9A, at least one side of each of the first metal plate 210 and the second metal plate 220 may be overlapped to face each other, and the metal bridge 230 may be interposed in the entire facing area. It is bonded to the metal plates 210 and 220.

9b and 9c have a different formation area of the metal bridge 230 interposed between the metal plates 210 and 220 when compared with the structure shown in FIG. 9a. That is, the metal bridge 230 is formed only on one side and the other side of the periphery of the region in which the metal plates 210 and 220 face each other. In this case, when the overcurrent occurs in the battery module 1, it is possible to expect the effect that the bus bar 200a can be quickly broken. Although not shown in the drawings, the metal bridge 230 may be formed in the entire circumference of the facing area, of course. In this case, a faster breaking effect can be expected for the overcurrent compared to the structure shown in FIG. 9A, and a better bonding force between the metal plates 210 and 220 can be expected as compared to the structure shown in FIGS. 9B and 9C. .

Next, a bus bar 200b according to another embodiment of the present invention will be described with reference to FIG. 10.

The bus bar 200b illustrated in FIG. 10 differs from the bus bar 200a illustrated in FIG. 5 in that a rivet 240 is further formed between the metal plates 210 and 220 and the metal bridge 230. The rivet 240 increases the bonding force between the metal plates 210 and 220 and the metal bridge 230.

Meanwhile, in FIG. 10, only the case where the rivet 240 is additionally applied to the bus bar 200a illustrated in FIG. 5 is further illustrated. However, the present invention is not limited thereto, and the present invention may be applied to the structures illustrated in FIGS. 6 to 7C. It is.

Next, a bus bar 200c according to another embodiment of the present invention will be described with reference to FIG. 11.

The bus bar 200c shown in FIG. 11 has tapered portions N1 and N2 formed so that opposite sides of the metal plates 210 and 220 are narrowed toward the ends, compared to the bus bar 200a shown in FIG. 5. different. In this case, as compared with the bus bar 200a shown in FIG. 5, the electrical resistance at the tapered portions N1 and N2 is increased, thereby generating more heat when an overcurrent occurs, thereby causing the bus bar 200c to Rapid breakage is possible.

11 illustrates only a case in which the tapered portions N1 and N2 are additionally formed in the bus bar 200a illustrated in FIG. 5, the present invention is not limited thereto, and the tapered portion may also be used in the structures shown in FIGS. 6 to 9C. Obviously, the (N1, N2) structure can be applied. In particular, when the bus bar 200a shown in FIG. 11 is combined with a structure that widens the contact area between the metal plates 210 and 220 and the metal bridge 230 as shown in FIGS. 7A to 7C, While the rapid breaking of 200c) is possible, not only the bonding force between the metal plates 210 and 220 is excellent, but also the contact resistance is low.

Next, referring to FIG. 12, a short-circuit test process and results of an experiment on the battery module 1 to which the bus bar 200a is applied will be described.

The short circuit experiment was performed on the battery module 1 to which the bus bar 200a having the form shown in FIG. 8A was applied, and the conditions were as follows:

Output voltage of battery module: 64.5V (15 unit cells with 4.3V output voltage connected in series)

Resistance value between external terminals: 5 mΩ

SOC (state of charge) of battery module: 100%

As a result of the experiment under the above conditions, as shown in FIG. 12, the voltage of the battery module 1 measured between the external terminals 311 was maintained at about 65V for about 50 seconds and then dropped to 0V. That is, at about 50 seconds after the start of the experiment, the bus bar was broken by the short circuit current, and the temperature measured in the unit cell was kept constant at about 23 ° C. during the short circuit experiment.

As a result, the bus bar 200a applied to the battery module 1 according to the present invention can secure safety on the use of a secondary battery by quickly cutting off a short circuit current before the temperature of the unit cell increases substantially in the event of a short circuit. It can be seen.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

Claims (21)

1. At least one unit cell;

   A case accommodating the unit cell;

   A bus bar electrically connected to the unit cell;

   The bus bar,

   A first metal plate;

   A second metal plate positioned to be spaced apart from the first metal plate; And

   And a metal bridge connecting between the first metal plate and the second metal plate and having a lower melting point than the metal plate.
2. The method of claim 1,

   The metal bridge is a battery module, characterized in that the lead-free alloy containing tin (Sn) and copper (Cu) as a main component.
3. The method of claim 2,

   The tin content is 80 to 98wt%,

   The copper content is a battery module, characterized in that 2 to 20wt%.
4. The method of claim 3,

   The metal bridge further comprises at least one additional metal selected from nickel (Ni), zinc (Zn) and silver (Ag).
5. The method of claim 4, wherein

   The content of the additional metal battery module, characterized in that 0.01 to 10wt%.
6. The method of claim 1,

   The metal bridge has a melting point of 150 to 300 ℃ battery module, characterized in that.
7. The method of claim 1,

   The first metal plate and the second metal plate is a battery module, characterized in that located on the same plane with a predetermined gap.
8. The method of claim 7, wherein

   And the metal bridge is joined to the first metal plate and the second metal plate on either or both sides of the first metal plate and the second metal plate.
9. The method of claim 7, wherein

   The first metal plate and the second metal plate have accommodation grooves formed in at least one of the upper surface or the lower surface of each one end portion facing each other,

   The metal bridge has a size and shape corresponding to that of the groove, and is accommodated in a space formed by the interlocking of the grooves to be bonded to the first metal plate and the second metal plate.
10. The method of claim 7, wherein

    The first metal plate and the second metal plate have a first bent portion and a second bent portion formed at one end of each of which face each other,

    And the metal bridge is accommodated in a space formed by the interlocking of the first bent portion and the second bent portion and bonded to the first metal plate and the second metal plate.
11. The method of claim 7, wherein

    The first metal plate and the second metal plate has a receiving groove formed to a certain depth from the surface facing each other,

    The metal bridge is a battery module, characterized in that one side and the other side is respectively inserted into the receiving groove and bonded to the metal plate.
12. The method of claim 7, wherein

    And the metal bridge is directly interposed between surfaces where the first metal plate and the second metal plate are opposed to each other and bonded to the first metal plate and the second metal plate.
13. The method of claim 12,

    And the opposing surface has an inclined surface shape tapered in the metal soldering bridge direction.
14. The method of claim 1,

    One side of each of the first metal plate and the second metal plate is positioned so that at least a portion thereof overlaps to face each other,

    And the metal bridge is interposed in the facing area and bonded to the first metal plate and the second metal plate.
15. The method of claim 1,

    One side of each of the first metal plate and the second metal plate is positioned so that at least a portion thereof overlaps to face each other,

    The metal bridge is a battery module, characterized in that formed on one side and the other side facing each other of the circumference of the facing area.
16. The method of claim 1,

    One side of each of the first metal plate and the second metal plate is positioned so that at least a portion thereof overlaps to face each other,

    And the metal bridge is formed over the entire circumference of the facing area.
17. The method of claim 1,

    The battery module further comprises a rivet for fixing between the first metal plate and the metal bridge and between the second metal plate and the metal bridge.
18. The method of claim 1,

    The first metal plate and the second metal plate is a battery module, characterized in that the one side facing each other has a tapered shape to narrow toward the end.
19. The method of claim 1,

    Further comprising an external terminal installed on one side of the case,

    The bus bar connects the unit cell and the external terminal.
20. At least one unit cell including a positive lead and a negative lead;

    A case accommodating the unit cell;

    A first bus bar connected to the anode lead; And

    A second bus bar connected to the cathode lead,

    The second bus bar,

    A first metal plate;

    A second metal plate positioned to be spaced apart from the first metal plate; And

    And a metal bridge connecting between the first metal plate and the second metal plate and having a lower melting point than the metal plate.
21. As a bus applied to the battery module,

    A first metal plate;

    A second metal plate positioned to be spaced apart from the first metal plate; And

    And a metal bridge connecting the first metal plate and the second metal plate, the metal bridge having a lower melting point than the metal plate.

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